TAMPA — After 23 years on death row, Wayne Tompkins has a day to live.

Barring any last-minute relief from his pending state and federal appeals, the 51-year-old former Tampa resident will be executed at 6 p.m. Wednesday for strangling his girlfriend's daughter and burying her body beneath the home where they lived.

Prosecutors say Tompkins tried to force himself on 15-year-old Lisa DeCarr and killed her when she resisted. With no physical evidence linking him to the murder, the state relied on testimony from three key witnesses to win a conviction.

Therein lies the problem, say Tompkins' lawyers, who have long attacked the credibility of those witnesses and the reliability of what they said.

"The evidence against Mr. Tompkins is just absurd," attorney Martin McClain said.

Jurors didn't think so. Neither did the circuit judge who sentenced Tompkins to death, nor the long list of state and federal judges who have denied the inmate's litany of appeals.

McClain says none of them had the benefit of DNA testing that was conducted only recently and that he argues remains incomplete. He believes the keys to the case could be locked inside this biological material. He's running out of time to prove it.•••Lisa DeCarr was initially reported as a runaway after she disappeared on March 24, 1983, from her Southeast Seminole Heights home. She had been suspended from school for smoking; those close to her thought she might be pregnant.

Perceptions changed in June 1984 with the discovery of a shallow grave below the porch of her home at 1225 E Osborne Ave. In about a foot of dirt, searchers found skeletal remains in a pink bathrobe, its sash tied tightly around the neck bones.

The robe belonged to Lisa, her mother said. She told police that Tompkins, her live-in boyfriend, had been at home alone with Lisa the day she disappeared.

Tompkins, then 27, was arrested that fall and put on trial a year later. By then, he had already pleaded guilty and was serving time for abducting and raping two convenience store clerks in Pasco County.

Prosecutors said three witnesses would provide "the overwhelming evidence" that he killed Lisa: her mother, who said she had last seen her daughter in a pink robe; her best friend, who said she had seen Tompkins and Lisa struggling on the couch as he tried to take off her clothes on the day prosecutors say she died; and a jail cell mate, who said Tompkins told him the details of the killing, down to how he buried her with her purse and clothes to make it look as if she'd run away.

But last November, the former cell mate claimed that the prosecutor, Mike Benito, had instructed him to include the purse detail in his testimony even though the informer didn't recall hearing that from Tompkins.

Benito denied doing so.

Florida Supreme Court Justice Harry Lee Anstead said the disclosure could have changed a jury's evaluation of the case. His colleagues disagreed, saying the main thrust of the informer's testimony had not changed, and denied Tompkins' appeal.

Appeals courts have shot down most of Tompkins' arguments. He got his best chance at life in April 2001, when Hillsborough Circuit Judge Daniel Perry granted him a new sentencing hearing just two weeks before he was scheduled to be executed. Perry ruled that the trial judge — the late Harry Lee Coe, nicknamed "Hanging Harry" and known for handing down harsh punishments quickly — had improperly handled the sentencing.

But in 2003, the state Supreme Court ruled that no new hearing was necessary. Tompkins continued to pursue appeals.

It wasn't until December that Gov. Charlie Crist ordered the DNA testing Tompkins' attorneys had been seeking for years.

As part of their efforts to exonerate Tompkins, who has always maintained his innocence, McClain and his colleague, Neal Dupree, want proof that the remains are actually Lisa's. Their suspicion stems from reports that people saw or heard from Lisa after the date that prosecutors contend she died, claims that have never been substantiated in court.

"Pink bathrobes are pretty much a dime a dozen," McClain said, referring to one of the key pieces of evidence used to identify Lisa.

The attorneys also wonder if hair and blood evidence that they only recently learned existed might point to a different killer.

So far, that hasn't happened. The DNA test results from the FBI and Florida Department of Law Enforcement came back last month as inconclusive.

On Monday, McClain and Dupree requested a stay of execution. They need more time, they said, to pursue further testing.

In a pointed response, prosecutors noted that the Florida Supreme Court has ruled that such DNA tests would have "no reasonable probability" of vindicating Tompkins.